Applicator means



Filed Nov. 16, 1967 3 Sheets-Shea?l 2 FIGLIO.

FIGS.

TocmM KOHM J. KOHN v APPLIcAToR MEANS April 14, 1970 5 Sheets-Sheet 5 Filed Nov. 16. 1967 @YMS EGE A Mvemofe: Toncnm Komm 6&1

United States Patent O1 iice 3,505,858 Patented Apr. 14, 1970 3,505,858 APPLICATOR MEANS Joachim Kohn, London, England, assignor to Shandon Scientific Company Limited, London, England, a British company Filed Nov. 16, 1967, Ser. No. 683,560 Claims priority, application Great Britain, Nov. 25, 1966, 52,987/ 66 Int. Cl. G01n 31 /08, l/00 U.S. Cl. 73-61.1 10 Claims ABSTRACT OF THE DISCLOSURE An elongated plate-like applicator provided in one are represented by respective colinearly arranged streaks on the substrate. The run can then commence.

It will be appreciated that the formation of a number of individual colinearly arranged streaks on a substrate by the method outlined above takes time and if several runs on each sample are to be performed on several substrates simultaneously the time taken to streak the longitudinal edge with cut-outs which separate the edge v into a plurality of spaced and aligned edge elements formed with longitudinally aligned liquid holding channels of a uniform cross-section. A pallet is provided with a row of spaced liquid receiving stations into which the respective edge elements of the applicator may be dipped to lill the channels, whereupon the applicator may be used to simultaneously transfer a plurality of liquid samples of substantially the same volume to a work surface.

'I'his invention relates to applicators and is specifically concerned with an applicator for forming on a substrate a number of spaced liquid sample streaks arranged colinearly.

In techniques such as electrophoresis and chromatography it is often required to conduct simultaneously a number of parallel runs on different samples. During the runs constituents of the samples travel at different speeds along the substrates and thus after a given length of time they are separated spacially from one another. By comparing the runs with a calibration run performed under the same conditions it is possible to determine the nature of the constituents by means of a direct comparison.

The substrate is normally prepared for a run by forming streaks of the diierent samples on the surface at one end of the substrate. The streaks are normally arranged colinearly and at right angles to the direction in which constituents of the streaks are to migrate during the run. Thus the different constituents travel as discrete bands at right angles to the aligned streaks. To ensure spacial separation of the bands when the respective constituents of the bands travel at only slightly differing speeds it is important that the sample streak should have negligible width. Inevitably some spreading of the constituents in the direction of the run occurs but by arranging for the streak to have negligible width there is a reasonable chance of spacial separation of bands travelling at nearly the same speed by the time that the leading band approaches the end of the substrate remote from the streaks.

To obtain streaks of different samples of approximately the same length and of little width, it has been proposed to use as an applicator a pair of parallel wires arranged side by side. This simple applicator is dipped into a liquid sample which distributes itself uniformly between the two wires so that the volume of liquid per unit length of wire is the same. The two wires are then placed on the substrate at the position where the streak is to be formed so that the liquid between the wires is transferred to the substrate and forms on it a sample streak con-V taining substantially the same Volume of liquid per unit length of the streak. The applicator is then cleaned and is dipped in the next sample which is required to form the adjacent streak. The process is repeated, cleaning the applicator between each sample, until all of the samples substrates may -be unacceptably long.

An object of this invention is the provision of an improved applicator.

In accordance with the present invention an applicator for forming on a substrate a number of spaced colinear liquid sample streaks each having substantially the same volume of sample liquid per unit length, comprises a body portion having a straight, thin, interrupted applicating edge adapted to be touched lightly against the substrate and provided by a number of straight spaced edgeelements aligned with one another and providing a number of colinearly arranged liquid-holding channels of the same cross-section.

In one arrangement of the invention the interrupted applicating edge is of generally castellated form. Each of the castellations terminates in an edge surface formed with a longitudinally extending groove providing one of the liquid-holding channels. The edge-elements of the applicator are provided by the grooved edge surfaces which are 'aligned with one another.

In use, the applicator has its liquid-holding grooves filled with different sample liquids and its applicating edge is then touched lightly against the surface of the substrate at the position where the aligned streaks are to be formed. As the liquid-holding grooves have substantially the same cross-section each of them deposits on the substrate a thin elongated sample streak which is colinear with all of the other sample streaks and in which the sample liquid is uniformly distributed along the length of the streak. In this manner a large number of streaks may be formed simultaneously on the substrate, thus shortening the time necessary to prepare the substrate for the run.

In another arrangement of the invention the edge-elements of the applicator com-prise spaced pairs of elongated members arranged side-by-side and extending parallel to one another to dene between their opposed surfaces the liquid-holding channels. The height of each member is preferably relatively small, being of the order of, and preferably less than the overall width of each pair of members. Such members are conveniently formed by strip portions of two thin parallel sheets of similar shape and having sandwiched between them a suitably shaped spacer layer. The interruptions between neighbouring pairs of strip portions are suitably formed by notches cut out of the applicating edge to leave it in generally castellated form. The central portions of the castellations are conveniently formed with windows each having one edge extending parallel to the end edge of the castellation from which it is formed. The strip portion is thus formed between the edge of the windows and the end edge of the castellation. A small spacer block may be placed between opposite ends of each pair of strip-portions to impart some rigidity to them and to maintain them spacially separated to the desired extent. Such a construction of applicator has the advantage that if it is dipped deeply into sample liquid, the windows on the applicating edge limit the vertical surface area of the applicator onto which sample liquid can cling so that the quantity of liquid transferred by the applicator to the substrate is substantially unaffeced by the height of the applicating edge immersed.

Preferably the applicator is used in combination with a pallet having a line of stations, such as recesses, holding respectively different liquid samples to be applied to the substrate by the applicator, the spacing between the stations being less than the spacing between the liquid-holding channels of the applicator and each station being slightly longer, measured in the direction of the line of stations, than the length of the channel of the applicator which is to contact it. Thus individual samples may be held in respective stations of the pallet and the channels of the applicator filled by contacting the applicating edge with the stations of the pallet. The different sample liquids in respective channels may then be transferred to the substrate.

In its simplest form the applicator may comprise a flat plate having a castellated applicating edge. The end edges of the castellations provide aligned edge-surfaces and the marginal portion of the plate remote from the castellated edge may be folded back on itself to provide a finger grip and to impart rigidity to the applicator.

Although the applicator may be made of any suitable material it is conveniently made of metal. The edge-surfaces are suitably coplanar although in cross-section they may, for example, be rounded, tapered, or otherwise shaped and they are preferably formed with a symmetrically arranged 90 degree groove of .01 inch width.

The invention will now be described in more detail, by Way of examples, with reference to the accompanying drawings, in which:

FIGURE 1 shows an applicator in plan;

FIGURE 2 shows the applicator viewed in the direction of the arrow A in FIGURE 1;

FIGURE 3 is an end view of the applicator;

FIGURE 4 is a cross-section through part of the applicator and is taken on the line indicated by the arrows IV-IV in FIGURE 1;

FIGURE 5 is a plan view of one form of pallet for use with the applicator;

FIGURE 6 is a plan view of another form of pallet;

FIGURE 7 shows the pallet of FIGURE 6 viewed in the direction of the arrow B;

FIGURE 8 is an end view of the pallet of FIGURE 7;

FIGURE 9 is a plan view of a second form of applicator of which the central portion has been broken away to expose interior detail;,

FIGURE l is a section through FIGURE 9 taken on the line and in the direction of the arrows X-X in that figure;

FIGURE 1l is a scrap perspective view of a corner portion of a castellation formed on an applicating edge of the applicator of FIGURE 9, looking generally in the direction of the arrow XI; and

'FIGURES 12, 13 and 14 are respectively plan and two detail views of a third form of applicator.

Referring jointly to FIGURES 1, 2 and 3, an applicator 1 comprises a at, generally rectangular metal plate made from inert metal and of 20 standard wire gauge. The length of the plate is 139 mm. and the height of the plate is 1% before the formation of a simple stiffening handle 2 by folding back over the plate a 3/8 high marginal portion 3 of one longer side. The stifening handle 2 thus reduces the height of the plate to 11/2 The other longer edge 4 of the applicator provides ten castellations each 6 mm. long. Nine of the castellations 5, counting from one end 6, are spaced by cut-outs 7 each 8 mm. wide and 3/8 long. A wider cut-out 8 of 12 mm. width is formed between a pair of castellations 5 at the other end of the applicator and serves to polarise it.

The free ends of the castellations 5 provide ten straight spaced aligned edge-elements or surfaces 10V at right angles to the plane of the plate and coplanar with one another. Each edge surface 10 is an elongated rectangle and a V-shaped groove 11 of uniform depth extends symmetrically between its opposite ends. The flanks 12 of the groove 11 subtend an angle of 90 and the width across the mouth of the groove measured in the plane of the edge surface 10 lies between 0.01 and 0.015 of an inch. The grooves 11 are formed simulatneously by a suitable tool which travels the full length of the castellated edge 4 of the applicator during its manufacture. Thus all of the grooves can be made of the same uniform cross-section to provide substantially identical liquid holding channels.

A pallet 12 shown in FIGURE 5 is used in conjunction with the applicator 1 and comprises a rectangular flat glass dish 13 having a line of stations formed by ten recesses 14 formed in one face and each framed by a shallow wall 15. The recesses 14 are rectangular but they may, of course, be any shape. Each recess 10 is 10 mm. long measured in the direction of the line, and 5 mm. wide measured at right angles to the line. The centre lines of the recesses 10 are spaced 14 mm. from one another so that a gap 16 of 7 mm. occurs between each recess 10. The overall length of the pallet 12 is 170 mm. and its width is 40 mm. The line of recesses is spaced 12 mm. in from one longer edge `17. Although nine of the recesses are spaced from one another by 4 mm. the spacing between the first and second recess is increased to 8 mm., as shown at 18, for polarising purposes.

To use the applicator samples of the different liquids under investigation are placed in respective recesses 14 in the pallet 12. When the sample volumes in all of the recesses 14 are approximately the same the applicator 1 is placed on the pallet 12 so that the grooved edge surfaces 10 of the castellations 5 dip into respective recesses 14. Thus each of the grooves 11 now holds approximately the same volume of sample liquid uniformly distributed along its length.

The applicator is then transferred to the substrate (not shown) and its applicating edge is touched lightly against its surface at the position where the aligned sample streaks are to be formed. Approximately the same proportion of the liquid in each of the grooves is transferred to the substrate to form on it ten aligned straight streaks each of narrow width and each containing approximately the same volume of liquid uniformly distributed along its length.

FIGURES 6 to 8 show an alternative pallet 20 to that shown in FIGURE 5 and which is more suited to occasions where there are only limited volumes available of the samples to be streaked.

The pallet 20 comprises a rectangular flat-faced glassl slab mm. long, 26 mm. wide and 6.5 mm. thick. One face 21 of the slab has parallel channels 22 cut across it each 2 mm. deep to leave ten rectangular coplanar lands 23 each of which is 8 to 10 mm. long, measured parallel to the longer sides or the slab. One of the channels, referenced 22', is wider than the others, being 8 mm. wide, and is disposed between the first and second land counting from the left-hand end of the pallet 20 shown in FIGURE 6. Channel 22 is provided for polarising purposes.

To use the pallet 20 the different samples are smeared onto the coplanar surfaces of respective lands 23. The same applicator as described with reference to FIGURES 1 to 4 is used with the pallet 20. To charge the applicator its edge surface 10 is placed face down onto the channeled Vface of the pallet so that the castellations 5 contact respective stations provided by the lands 23.

Various modifications to the above described applicator are possible. For example, the edge surface 10v of theapplicator formed with the groove 11 may be rounded, instead of flat as shown in FIGURE 4, so that the mouth of the groove 11 is formed betwen two sharp edges rather than between two thin coplanar flats.

Turning now to the applicator shown in the remaining FIGURES 9 to 1l, it has an applicating edge 30 formed by `castellations 31 spaced from one another by V-shaped notches 32 cut out from the edge. The applicator is formed by two identically shaped metal sheets 33, 34 arranged side-byside and having a spacer layer 35 sandwiched between them. The layer 35 terminates close to the root portions of the castellations 31 which are each formed with a rectangular window 36. One edge of the window is parallel to the free end of the castellation to provide therebetween an elongated narrow strip portion 37. The strip portions 37 provide longitudinally spaced edge-elements and are arranged in pairs to define between their opposed surfaces liquid-holding channels as shown at 40 in FIGURE 11. The strip portions 37 of each pair are held in spaced parallel relationship at their ends by spacer blocks 38 arranged in the corners of the castellations and of the same width as the spacer' layer 35. The applicator is provided with numbers 1 to 10 identifying respective castellations to simplify use.

The applicator is used in the same way as that described earlier. When dipped into the liquid samples of the pallet the liquid fills the liquid-holding channels 40 so that each contains the same volume of liquid per unit length. When the applicating edge is touched lightly against the substrate, substantially the same volume of liquid is transferred by each of the channels.

An advantage of the applicator of FIGURES 9 to 11 is that the windows 36 act to limit the wetted area of the applicating edge when dipped deeply into the liquid of the palle. When the applicating edge is withdrawn from the pallet, the wetted area is substantially confined to the strip portions and the channel between them. The height of the channel is of the same order as its Width so that the amount of liquid clinging to the exposed surfaces of the strip portions is quite small. To reduce the effect of such clinging liquid still further, the height of each channel 40 is suitably less than the overall width of the pair of strip portions.

The third form of applicator shown in FIGURES 12, 13 and 14 is constructed from a single strip of metal 41 of suitable thickness by a spark erosion technique. The metal strip 41 is cut along one longer side to provide castellations 42, and rectangular windows 43 are cut out of respective castellations 42. The free edge surfaces 44 of respective castellations 42 are each formed with a thin rectangular slit 45 by a spark erosion technique. The slits 45 extend through to the windows 43 and provide colinearly arranged liquid-holding channels of the same cross-section. The metal of the castellations 42 left at the ends of the slits 45 provides spacers and strengtheners for each of two thin parallel strip portions 46 between which each slit 45 is formed.

It will be appreciated that by using the applicator of the invention a large number of substrates may be quickly streaked with substantially the same quantities of liquid sample.

I claim:

1. An applicator for simultaneously applying to a work surface a row of spaced elongated liquid samples each having substantially the same liquid volume per unit length, said applicator comprising an elongated plate-like body provided in one longitudinal edge thereof with a plurality of cut-outs which separate said longitudinal edge into a plurality of longitudinally spaced discrete castellations, said installations having elongated edge elements disposed in longitudinal alignment, said edge elements being provided with liquid holding channels of a uniform crosssection extending longitudinally in the edge elements.

2. An applicator as set forth in claim 1, in which said edge-elements are spaced from one another by distances, one of said distances nearer one end of the applicator body being of a different size than others whereby polarisation of the applicator is achieved.

3. An applicator as set forth in claim 1, in which said edge-elements comprise end surfaces which are coplanar elongated rectangles, and the channels comprise grooves of V-shaped cross-section formed in said end surfaces.

4. An applicator as claimed in claim 1, in which said edge-elements each comprise a pair of parallel elongated members spaced by a gap providing one of said liquidholding channels.

5. The applicator as defined in claim 1 wherein said plate-like body comprises a pair of spaced parallel sheets and a spacer layer sandwiched between said sheets, said sheets having longitudinal edge portions projecting outwardly beyond said spacer layer and provided with said cut-outs whereby said edge elements exist in pairs with the elements in each pair being transversely spaced by the thickness of said spacer layer between the sheets, said pairs of edge elements being formed with windows and strip-like edge portions of the elements beyond said windows define said liquid holding channels therebetween.

6. The applicator as defined in claim 5 together with spacer blocks provided between said strip-like edge portions of said edge elements at the ends of said liquid holding channels for holding the strip-like edge portions in spaced parallel relation.

7. An applicator and a pallet in combination, said applicator comprising an elongated plate-like body provided in one longitudinal edge thereof with a plurality of cutouts which separate said longitudinal edge into a plurality of longitudinally spaced elongated edge elements disposed in longitudinal alignment, said edge elements being provided with liquid holding channels of a uni-form crosssection extending longitudinally in the edge elements, said pallet being provided with a row of liquid sample receiving stations which are isolated from one another and are adapted for simultaneous engagement by the respective edge elements of said applicator for filling the liquid holding channels in 'said elements.

8. The combination set forth in claim 7, in which each station of the pallet is framed by a shallow boundary wall.

9'. An applicator as set forth in claim 7, in which the stations of the pallet comprise coplanar lands isolated from one another by channels.

10. In combination an applicator and a pallet, said applicator comprising an elongated plate-like body provided in one longitudinal edge thereof with a plurality of cutouts which separate said longitudinal edge into a plurality of longitudinally spaced elongated edge elements disposed in longitudinal alignment, said edge elements being provided with liquid holding grooves of a uniform V-shaped cross-section extending longitudinally in the edge elements, the other longitudinal edge of said body opposite from said edge elements forming a handle portion, the longitudinal spacing between two of said edge elements near one end of said body being different from the spacing between the other edge elements for purposes of polarisation, said pallet having a face provided with a row of liquid sample receiving stations and with isolating means between said stations and being polarised for simultaneous engagement by the respective edge elements of said applicator for filling the liquid holding grooves in said elements when applicator is correctly oriented with respect to the pallet.

References Cited UNITED STATES PATENTS 209,722 11/ 1878 Soennecken 33-41 743,865 11/1903 Hall 33-41 1,625,863 4/ 1927 McLarty 33-44 X 3,358,496 12/1967 Farmer 73-61.1

FOREIGN PATENTS 1,180,166 10/ 1964 Germany.

LOUIS R. PRINCE, Primary Examiner J. W. ROSKOS, Assistant Examiner U.S. Cl. X.R. 33-41; 73-425.4 

